An unexpected notifiable disease has been confirmed in Somerset by Dr Timm Konold, the Animal and Plant Health Agency (APHA)’s lead scientist for transmittable spongiform encephalopathies (TSEs). Bovine spongiform encephalopathy (BSE), more commonly referred to as mad cow disease, is a fatal brain disease in cattle, and any suspected cases must, by law, be reported to the APHA.
A case of classical BSE was identified and confirmed in September 2021 in a six-year-old cow that was unresponsive to treatment.
Classical BSE is linked to the ingestions of feedstuffs contaminated with the BSE pathogen, which was identified as the cause of the human variant Creutzfeldt-Jakob disease. Since the mad cow disease epidemic in the early 1990s, BSE has become a rare disease, which makes the origin of new cases extremely important to investigate. It is suggested that cases of classical BSE continue to occur due to residual contamination of feed, feed production or feed storage units.
A case occurring in 2021 is not unexpected; according to mathematical modelling by APHA scientists, an exponential decline in cases following the complete ban on feeding animal protein to livestock (1996) is expected. A longer timeframe for the decline was predicted in Great Britain due to the higher number of cases present at the time of the ban.
Epidemiological investigations were necessary to identify the suspected food-borne source. Due to the long time between exposure to the BSE pathogen and death for the disease, identifying the source of contamination is difficult. Consumption of the contaminated food source is likely to have occurred when the animal was a calf, and in this latest case, the animal was six when the disease was detected.
The investigation concluded that the most likely source was feed from a silo that had been on-farm since the 1980s. As the silo had never been thoroughly cleaned, it was suspected that it could contain traces of old feed that was inadvertently ingested by the animal.
Active monitoring for BSE in fallen stock will continue for the foreseeable future, although it is hoped that this latest case will be the last classical case of BSE in England.
Veterinarians and animal keepers must be aware of the clinical presentations of BSE and, as a notifiable disease, any suspicion of BSE must be reported to the APHA so it can be investigated. This especially applies to any downer cows that are not responding to veterinary treatment and have a clinical history indicative of a neurological disease (or if the animal is old enough to consider atypical BSE at usually eight years or older).
If you live in England as suspect a case of BSE, please call the Defra Rural Services Helpline on 03000 200 301. In Wales, contact 0300 303 8268. In Scotland, contact your local Field Services Office.
You can read more about this identified case of BSE on the APHA website.
